Day 3 — Your core loop works

Goal

You build exactly the one chain that defines your app — and nothing beside it.

Understand briefly

The core loop is why someone opens your app at all. It only counts once it runs through completely: from the action to a result people understand. Work with realistic local sample data instead of “test 1” and “test 2” — unrealistic data hides exactly the cases that catch up with you later.

Follow along

Paste this prompt into the AI tool you work with:

This is my core loop: [YOUR FOUR STEPS]

Implement the happy path only:
1. Implement the four steps in order, without error handling for now.
2. Create realistic local sample data — real names, real lengths, real edge cases.
3. Present the final result so a stranger understands it without explanation.

Do not build extra screens, settings or accounts.

Build it yourself

Walk the loop yourself three times: once fast, once slowly and once with the most unlikely input you can think of.

Verify

Only tick a box once you have really checked it. These criteria are the only way to finish this unit.

The core loop runs from start to finish without a detour.
I test with realistic sample data instead of placeholders.
The result is understandable without my explanation.

0 of 3 confirmed

Still open: 3 criteria

Self-check

Three questions about decisions you made today. There are no points and no grade — only the why. Every answer can be changed.

1. When does your core loop count as having run through once?

When every screen involved existsWhen it runs from the action to an understood resultWhen it runs through and looks good doing it

2. What do you test your core loop with?

With "test 1", "test 2", "asdf"With realistic sample dataWith as little data as possible, to stay fast

3. The result of your core loop appears on screen. When is it understandable?

When I can explain it in one sentenceWhen someone understands it without my explanationWhen the log shows the right values

0 of 3 answered

Next step

Tomorrow you take care of everything that is not the happy path.

Next: Day 4 — Your app survives bad days too

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